1. Field of the Invention
The present invention relates to a cross-connection apparatus for a tributary unit (TU)-12 signal included in a synchronous transfer module (STM)-N signal which is used for a connection signal between the synchronous digital hierarchy (SDR) network nodes.
2. Discussion of Related Art
A section overhead (SOH) and a path overhead (POH) which are allocated for operation administration and maintenance (OA&M) of the transmission signal become useless after their processing. Therefore, the TU-12 signal can be allocated to the area where those overheads existed originally. If the TU-12 is used as a test access signal, the entire switch network can be tested during the service. Meanwhile, an identifier (ID) byte and bit interleaved parity (BIP) byte for inserting/detecting a predetermined pattern can be allocated to the newly produced signal frame for the purpose of usefully monitoring an error occurring between the boards of a system, and testing the system.